“This has been a longtime favorite of my husband’s and this version has been on his personal playlist for all these years,” Hill said in a release on her website. “It was and sadly still is today an important message. This is for Tim.”

The country superstar doesn’t reveal exactly what the song is about, but there’s no denying the power of these intimate, emotional lyrics:

“Oh why, that’s what I keep asking, was there anything I could have said or done?…I had no clue you were masking a troubled soul…God only knows what went wrong, and why you would leave the stage in the middle of a song…”

“Why” is one of three previously unreleased songs included on Deep Tracks. The two others are “Boy” and “Come to Jesus,” another emotional track that Hill wrote in honor of her late mother, as well as her husband’s late father, Tug McGraw.

Listen to a clip from “Come to Jesus”:

Mom often asked if I would ever record a gospel album. Thankful she was able to hear this song before she took a seat on the glory train. pic.twitter.com/aTFeY1AerT

McGraw and Hill often inspire one another’s music, and the country power couple will soon take their collaboration to the next level. In October, they announced their upcoming joint world tour, Soul2Soul The World Tour 2017.